Having the characteristics or properties of chlorophyll, or belonging to organisms that contain chlorophyll.
From chlorophyll plus -aceous (Latin -aceus, having the quality of). The suffix -aceous indicates 'having the nature of,' similar to herbaceous or cretaceous.
Notice how -aceous appears in words describing fundamental properties—herbaceous plants are herb-like, cretaceous rocks contain chalk, so chlorophyllaceous literally means 'having the nature of chlorophyll,' which is a elegant way of describing photosynthetic organisms without listing them all.
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